jpa 2.0 annotation to a class with 2 ID pointing to two different tables

Question

I have this 3 entities E1, E2, E3. I want to know how I must note my E3 class has 2 primary key each pointing to a different table with additional fields.

@Entity
public class E1 extends RAP{
    /**
     * 
     */
}

@Entity
public abstract class E2{
    /**
     * 
     */
}

E3 class has 2 primary keys pointing to e1 and e2.

@Entity
public class E3 extends RAP{
    @Id
    @ManyToOne  
    @JoinColumn(name = "e1_id")
    private E1 e1;

    @Id
    @ManyToOne
    @JoinColumn(name = "e2_id")
    private E2 e2;

    private Double myfield1;
    private Double myfield2;
}

but there is a problem. like this...

This class has a composite primary key. It must use an ID class.

so i want to use some annotation without using @Embedded entity

You shouldn't have 2 primary keys, use Embedded, if you only want to index the field for fast access, or constraint to have nor repeated values, you can implement this with other methods, but each JPA should only have one ID field — Javier Toja, Sep 20 '16 at 10:16

score 1 · Answer 1 · edited May 23 '17 at 12:16

Here you have an example of how to specify constraints over multiple columns, and how declare relations between tables, also check this to have a reference about indexing in jpa 2.0, and the main differences with 2.1.

You problem looks like a perfect candidate for a hierarchical model and this link shows an example of how define and use this kind of models.

If you can explain what you want to archive a bit more, maybe we can find a more specific solution.

jpa 2.0 annotation to a class with 2 ID pointing to two different tables

1 Answers1